Foldable closures



May 30, 1961 J. ROSENFELD 2,986,210

FOLDABLE CLOSURES Filed Jan. 21, 1959 2 Sheets-Sheet 1 JOSEPH ROSENFELD INVENTOR,

ATTORNEY.

May 30, 1961 .1. ROSENFELD 7 2,986,210

FOLDABLE CLOSURES Filed Jan. 21, 1959 2 Sheets-Sheet 2 FIGA INVENTOR JOSEPH ROSENFELD,

ATTORNEY,

nited States Patent FOLDABLE CLOSURES JosephRosenfeld, 175-55 Liberty Ave., Jamaica, N.Y. Filed Jan. 21, 1959, Ser. No. 788,074

4 Claims. 01. 160-84) I The present invention relates to foldable doors and 'iv'all. sections of the accordian-fold type and more particularly .to mechanism to fold and unfold the door structure.

, v.In one type of closure in which the present invention is applicable, folding mechanism is suspended from an over head-track and supports apair of curtains which hang on said mechanism, one in front of it and one in back of it. When the mechanism is collapsed, each curtain folds accordian-wise, and when expanded, the folds in the curtains open; the extensible and contractable means employed being lazy tongs, generally, one along the upper region and the other along the bottom region of the door structure. I

, Since the bottom of the entire folding structure is free and the height and weight of the entire foldable door structure is appreciable, the lower part of the free side end of the door structure folds and unfolds faster than the upper part. Various attempts have heretofore been made to have the lazy tongs, all move in unison, but the folding mechanism does not present a rigidity sufiicient to overcome the faster movement of the bottom and the resulting jamming of the folding mechanism. Where some success along this line has been attained, the cost of the structure makes it commercially prohibitive and the mechanism adds undue weight, is intricate and otherwise objectionable. Itis therefore an object of this invention to provide a noveland improved folding door mechanism by which the door will open and close evenly and uniformly, that is, its free end will not slant but remain substantially true perpendicular. while said mechanism is manipulated.

Another object thereof, isto provide a novel and improved folding door mechanism, adaptable for all types of accordion-fold door structures, so that when supplied with means taught herein, they will operate properly and avoid,the.'objectionable incidents which have been the experience heretofore. "-"iA further object thereof is to provide novel'improvements in present folding door mechanism to attain the desirable features hereinabove mentioned, avoid jamming, and make it easy to open and close the door with little effort and in proper manner.

Still a further object of this invention is to provide a novel and improved folding door mechanism of the character described and having the attributes mentioned, which is reasonably cheap to manufacture, easy to use and eflicient in carrying out the purposes for which it is designed.

Other objects and advantages will become apparent as this disclosure proceeds.

For the practice of this invention, one form it may assume is to have the door folding mechanism comprise an upper lazy tongs suspended in known manner from an upper track and a lower lazy tongs. Usually, the axis means at the distal ends of the links comprising said tongs, is a thin rod positioned vertically and whose ends serve as axis pintles, joining corresponding sets of links Patented May 30, 1,961;

of both lazy tongs. Correspondiiig'ends of said tongs are associated, one. set with a fixed jamb and the other set to a .vertical stile alongthe manually-moved end of the door structure. Said mechanism carries foldable curtains at the front and at the back of it in well known manner. I equip said mechanism with spring means acting to close the lazy tongs, but ineffective to do so because the stress 1 in such spring means is a bit less than the force required to overcome the friction to open or close the door structure, regardless of the quantity of extension of the door structure. The nature of said springs is such that re gardless of the extent of their extension, the stress in them is always constant. Since I neutralize the friction, the working of the door structure to open and close, is made easy. In some instances, I arrange the spring means on the door. mechanism so, that it requires a little more force to move the lower lazy tongs than it takes to op erate'the upper lazy tongs. This compels the free stile of the door structure to remain vertical while the door is being opened or closed.

In the accompanying drawings forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

Fig. l is a front view of a folding door mechanism embodying the teachings of this invention. Said mechanism is shown in extended condition, meaning, the door is closed. This view is partly diagrammatic and is intended in particular to show'a preferred embodiment employing special spring means of the nature aforementioned.

Fig. 2 is a diagrammatic top plan view of Fig. 1.

Fig. 3 is a diagrammatic showing of a preferred form of the type spring means employed.

Fig.- 4 is a fragmentary perspective view of a corner portion of the folding door mechanism shown in Fig. 1.

In the drawings, the numeral 15 designates generally the mechanism of a folding door structure. In this particular embodiment illustrated, said mechanism comprises an upper lazy tongs denoted generally by the numeral 16 and a lower lazy tongs indicated generally by the numeral 17, both horizontally positioned with relatively thin rods 18, each of which acts as the pintles for corresponding distal ends of link pairs of both lazy tongs as is Well known in this art. All crossing links as 19 and 20, are pivotally joined at mid-section by an axis pin 21-, and selected spaced pintles of this kind of the upper lazy tongs 16, extend upward as 21', and there equipped with roller means 22 which is engaged'by the upper fixed track'23 for movement therealong. Along one side of the door opening, there is the vertical fixed jamb or stile 24. which carries the brackets 25, 26, to which the adjacent ends of the lazy tongs 1'6 and 17 are suitably associated. The free ends of both said lazy tongs are suitably associated with the brackets 27, 28 carried on the free vertical stile 30 which usually has the handle 29 between the tongs, for opening and closing the door. The links of the lazy tongs have suitable tabs as 31 for suspending a foldable front curtain 32 and a similar rear curtain 33. All of the above structure is well known, as specifically described.

These folding door structures are used usually for closing large openings or to form comparatively large partitions and are appreciably heavy. In many such installations as in assembly halls, schools, hospitals, public places and theatres, need be quickly openable. I therefore utilize spring means, a preferred embodiment of which is shown at 34. These are extensible and contractable, and in which regardless of the amount-of extension, the stress is substantially of constant value. This spring means is arranged in one or more places on the folding door mechanism as will be explained, to urge the lazy tongs to contract in length and are so chosen, that the aggregate stress in them when extended, shall be a bit less than is nec msary to overcome friction to move the folding door structure to open. Hence, very little force is required to open the door structure 15.

This spring 34 is made of a spring steel band whose ends are the inner turns respectively of spiral forms 35, 36. These spirals may be wound on centrally disposed rollers, spools or pulleys 37, 38 respectively and their inner ends may be secured to such pulleys respectively. These pulleys are revolvably mounted on two points of the folding door mechanism so that when the door is open, the spirals 35, 36 shall be in spaced relation, and since the action of this spring 34 is for the spirals to come together when separated, said pulleys are mounted on such pants of the folding door mechanism, which when brought together, will cause the lazy tongs 16, 17 ,to 'contract.

One manner of utilizing these springs is to embody them to act at each corner of the door structure respectively. As shown in Fig. 1, one terminal pulley of such a spring is mounted on each of the brackets 25, 26 27 and 28, and the other terminal pulleyof suchfsprings are respectively mounted on a pintle as 40 which pivotally connects a pair of crossing links as 41, 42. These associated links are away from the brackets at therespective end regions of the lazy tongs 1 6 and 17. These springs indicated in Fig. 1 as 34 and 34 in one set-up, are identical in strength and in all instances, their aggregate strength should be a bit less than the force requiredto overcome friction to open the folding door structure.

Having the same arrangement of said springs 34, 34' as shown in Fig. 1. I have found it beneficial tohave the lower spring 34' to be one of greater strength than the others which are of equal strength, or to have both springs 34 of equal strength, but greater than the strength of the springs 34. These arrangements aid in the accomplishment of making the lazy tongs 16 and 17 move in unison.

These springs herein discussed may be positioned horizontally as shown, or vertically if desired, and any suitable number of them may be employed. Without further illustration, it will be readily understood that even a single spring of the type described herein may be used connecting for instance the fixed stile 24 and the free stile 30, and another instance given as mere example also, the springs 34 in Fig. 1 may be omitted, hence using only the springs 34.

The spring 34 may be severed between its spirals 35, 36 and each part used in the manner of the whole, in which instance the pulley within the spiral would be rotatably mounted and the free end of such spiral would be fixed mounted to the two points on the folding door structure which come together when the door is opened. Also, said spring 34 may be severed between its spirals and the parted ends connected by' a pliant cable of rigid connector of elongated form. This would be practical for those installations where the points of mounting of the pulleys 37, 38 are distant.

This invention is capable of numerous forms and various applications in all types of folding doors and folding partitions in which curtains of all sorts fold accordian-wise. It is therefore intended and desired that the embodiment shown herein shall be deemed merely illustrative and not restrictive and that the patent shall cover all patentable novelty herein set forth; reference being had to the following claims rather than to the specific dmcription herein to indicate the scope of this invention.

I claim:

1. In combination, a suspended folding door structure of the accordian-fold type including a lazy tongs along the top region thereof and a lazyto'ngs along the bottom region thereof; both said lazy tongs being so associated with the door structure that upon extension of said tongs, the door structure will be caused to close and upon contraction of said tongs, the door structure will be caused to open; one side end of said door structure being fixed and its other side end being free; the ends of each of said lazy tongs being connected to said side ends of the door structure respectively and two constantly tensed tension spring means, each comprising a spiral formed of band material positioned near the free side end of the door structure and near each of said tongs respectively; said spirals being rotatably axially mounted on said free 'side end of the door structure and the outer turn of each of said spirals being connected respectively to a part of each of said lazy tongs respectively which moves away from and towards said free end of the door structure upon operation of said tongs to assume extended and contracted conditions respectively; the aggregate tension in said spring means being less than butnear equal to the force required to overcome friction to fold said'door structure to open the door and the tension in oneof'the spring means is of greater strength than that in theother spring means.

2. The article as defined in claim 1, wherein the lower spring means is of greater strength than the upper spring means.

3. The article as defined in claim 1, wherein each spring means includes a second spiral formed of band material, each rotatably mounted on that part of the lazy tongs which moves away from and towards the free side end of the door structure; the outer turns of both spirals of the respective spring means, being connected.

4. The article as defined in claim 3, whereinboth spirals of each of the spring means respectively, are formed in asingleband.

References Cited in the file of this patent UNITED STATES PATENTS 1,745,578 Kreissig Feb. 4, 1930 2,220,939 McGuire et al Nov. 2, 1940 2,635,282 Trammell et al. Apr. 21, 1953 2,670,198 Glaser et al. Feb. 23, 1954 2,732,594 Adams et a1. Jan. 31, 1956 

